Updated a header with a ETag for caching

img/image.js

@@ -1,4 +1,5 @@
 const utils = require('../utils/utils.js');
+const crypto = require('crypto');
 
 module.exports=
     {
@@ -10,13 +11,14 @@ module.exports=
         main: function(result, fileName, cache)
         {
             //result.contentType = 'image/png';
-            result.writeHead(200, {'Content-Type': 'image/png', 'Cache-Control': 'public, max-age=604800'});
 
             var img = cache.get(fileName);
             if(img == null)
             {
                 utils.include("." + fileName).then(function(content)
                 {
+                    var eTag = crypto.createHash('md5').update(img).digest('hex');
+                    result.writeHead(200, {'Content-Type': 'image/png', 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"'});
                     result.write(content);
                     result.end();
                     cache.put(content);
@@ -24,6 +26,8 @@ module.exports=
             }
             else
             {
+                var eTag = crypto.createHash('md5').update(img).digest('hex');
+                result.writeHead(200, {'Content-Type': 'image/png', 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"'});
                 result.write(img);
                 result.end();
             }

includes/includes.js

@@ -10,6 +10,8 @@ const FOOTER_FILE = "includes/footer.html";
 
 const Promise = require('promise');
 
+const crypto = require('crypto');
+
 module.exports =
 {
     /** Appends the header html section to the result which is
@@ -43,7 +45,7 @@ module.exports =
      */
     sendCSS: function(result, path, cache)
     {
-        result.writeHead(200, {'Content-Type': 'text/css', 'Cache-Control': 'public, max-age=604800'});
+
 
         var css = cache.get(path);
 
@@ -51,6 +53,8 @@ module.exports =
         {
             utils.include("./" + path).then(function(content)
             {
+                var eTag = crypto.createHash('md5').update(content).digest('hex');
+                result.writeHead(200, {'Content-Type': 'text/css', 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"'});
                 result.write(content);
                 result.end();
                 cache.put(path, content);
@@ -61,6 +65,8 @@ module.exports =
         }
         else
         {
+            var eTag = crypto.createHash('md5').update(css).digest('hex');
+            result.writeHead(200, {'Content-Type': 'text/css', 'Cache-Control': 'public, max-age=2678400', 'ETag': '"' + eTag + '"'});
             result.write(css);
             result.end();
         }